1. Field of the Invention
This invention pertains to the field of displays, particularly to those displays utilizing an electro-optic plate operable in the transverse bias mode and having crossover electrodes disposed on one side of the plate.
2. Description of the Prior Art
Recent developments in electro-optic materials have rendered these materials more useful as display devices. Developments have occurred in the class of transparent ferro-electric ceramic materials such as lanthanum modified lead zirconate titanate (PLZT) to produce materials with high optical transparency, significant electro-optic characteristics, high electromechanical coefficients, and ceramic structures of a polycrystalline nature. Use of these improved materials in display devices has now become more feasible and requires methods and structures to allow such use, for example, in the display device of the instant invention. A wide variety of applications have been proposed using electro-optic material, for example, as protective goggles for welders, as a photographic electronic shutter, as an optical switch, as a variable density transmission window, and as a color filter.
A prior art device using an electo-optic material, such as PLZT, is described in U.S. Pat. No. 3,737,211. A variable density optical filter is described in that patent operating in the transverse mode (the optic axes being transverse to the direction of light propagation). An interdigital array of co-planar electrodes is described as being positioned on one side of a thin ceramic wafer with an electric field being impressed between the electrodes. In the zero-field condition, light is not transmitted through a pair of crossed polarizers because the ceramic material is optically isotropic. When a polarizing voltage is applied, the electro-optic material provides a retardation of the light so that a component of the light is passed by the second of the crossed polarizers.